The present invention relates generally to a device that allows various elements to pass through the wall of a vehicle fuel tank and, more particularly, to a pass through device capable of being welded directly onto a wall of a polymeric vehicle fuel tank.
Modern automotive fuel tanks commonly have several critical components contained within their interior. For example, many fuel tanks in late-model vehicles typically contain a fuel pump and fuel filter disposed within the interior of the tank. This structure facilitates the modular approach to vehicle assembly currently being advocated by several automobile manufacturers.
The internalization of componentry, however, creates several issues regarding the structure of the fuel tank. For example, necessary communicative elements of the internalized components must pass through the wall of the fuel tank. An electric fuel pump requires an electrical supply line to provide the electricity needed for operation. As a consequence, this line must extend from the energy source, through the wall of the fuel tank, and to the fuel pump. Furthermore, the fuel pump forces fuel out of the tank and to the engine through a fuel supply line. This line must therefore pass from the interior of the fuel tank, through the wall of the tank, and to the engine. Thus, at a minimum, an electrical connection and fuel line must pass through the wall of a fuel tank containing an internalized fuel pump. Depending on the arrangement and properties of the fuel tank and pump, other elements, such as fuel return lines and vapor lines, may also need to pass through the wall of the fuel tank.
Various means exist for providing the necessary conduit through which these communicative elements can pass. For example, some internal fuel pumps have flanges for mounting the base of the pump to a wall of the fuel tank. These flanges are typically secured to the tank via a secondary means of attachment, such as nut and bolt connections or have a threaded base that interacts with a threaded opening in the wall of the fuel tank, sometimes referred to as a Mason jar connection. With the various communicative elements disposed on the underside of the base of the pump, pass-through of the elements is achieved when the fuel pump is secured in place. Due to these secondary means of attachment, fuel pumps employing these technologies typically require the inclusion of a gasket element to ensure a complete seal between the wall of the fuel tank and the fuel pump. Also, the use of such secondary means of attachment typically increases the size of the pass-through portion due to the need to include space for nuts, threads and the like. This larger size necessitates a larger main opening in the fuel tank which provides more opportunity for hydrocarbon permeation.
The seal between any pass-through device and the wall of the tank presents an opportunity for permeation of hydrocarbons through the joint. For example, in a seal utilizing a secondary means of attachment and a gasket, the attachment means may, over time or abruptly, loosen, or the gasket may crack or split. In these situations, the advantages of a modular approach to assembly, e.g., savings of time and expense during manufacturing, may later be defeated by the need for repair or replacement.
It is known in the prior art to use fuel tanks made from polymeric materials, such as polyethylene, in automotive vehicles. These polymeric materials impart various advantageous features onto the fuel tank, including resistance to corrosion, flexibility in design, and decreased overall weight. Devices can be secured to these polymeric fuel tanks in a variety of ways, including via threaded connections and secondary means of attachments, as mentioned above. However, polymeric materials offer another advantage: weldability to similar materials. A weld joint between similar materials avoids the need for secondary means of attachment and provides a strong interface between the two objects.
Considering the above, a pass-through device designed specifically for polymeric fuel tanks will offer several advantages. For example, the device will provide the communicative paths that are necessary for internalized components, while allowing for a stronger joint, i.e., a weld joint, by eliminating the need for a secondary means of attachment. Ultimately, such a device will enhance the operation of internalized component fuel tanks by lessening the opportunity for compromise of the seal between the tank and the pass-through. Also, such a device, appropriately composed, will reduce the ability of hydrocarbons to permeate through the joint between the device and the fuel tank.
The present invention provides a pass-through device for internalized component vehicle fuel tanks that takes advantage of the polymeric nature of most modern fuel tanks. At a minimum, the pass-through device contains a communicative passageway for the supply fuel line and a through opening for a push-through electrical connector. Also, the pass-through device may contain additional communicative passageway for elements such as fuel return lines and purge and fresh air inlets to a carbon canister.
The pass through device of the present invention comprises three components: a main body made of a barrier type material, such as nylon, a mounting plate of material similar to the material of the fuel tank, and at least one communicative passageway. Preferably, the mounting plate is composed of high density polyethylene. The main body is bonded to the mounting plate and may define the various communicative passageways. The nylon composition of the main body provides a barrier to hydrocarbon emissions, thereby lowering the permeation associated with the joint between the fuel tank and the pass-through device. The mounting plate provides a circumferential surface for weldably connecting the pass-through device to a polymeric fuel tank. This allows the pass-through device to be directly welded to the wall of the fuel tank, providing a superior joint between the pass-through and the fuel tank, and eliminating the need for the use of a secondary means of attachment and/or gasket. As a consequence, the pass-through device can be made relatively smaller than pass-through members that utilize a secondary means of attachment. Therefore, the structure and composition of the pass-through device according to the present invention allows several communicative elements to pass through a relatively smaller opening in the wall of a polymeric fuel tank.